High Quality Content by WIKIPEDIA articles! The rainbow shark, Epalzeorhynchos frenatum, is a popular freshwater community-tank aquarium fish of the Cyprinidae family. It is also variously known as the ruby shark, red-fin shark, red-finned shark, rainbow sharkminnow, green fringelip labeo, whitefin shark and whitetail sharkminnow. Unlike true sharks, which belong to the Chondrichthyes ("cartilagenous fishes") lineage, the rainbow shark is an Actinopterygiian ("ray-finned fish").